Power Line Communication Technology, "HD-PLC"*1

Problem-solving of IoT society from outlets.

Even before the emergence of the IoT society, whereby the goal is for everything to be connected together via the Internet, wireless networks have posed problems because of communication constraints, instability, and very high installation costs. As one possible solution to these issues, research has been ongoing in the field of power line communication (PLC) whereby power lines, including accessible outlets and other existing lines, are used for both power supply and wired-network communication.

Left photo: “Two-lamp cluster” (which came to be commonly known as a “two-pronged socket”) enables sharing of a power source between a lamp and an appliance.  Right photo: Typical outlets that can be used as power outlets or a wired-network.

In the very first days of domestic electricity, when a lamp socket was the only power supply port in a house, Konosuke Matsushita, the founder of Panasonic, invented the "two-lamp cluster" (which came to be commonly known as a "two-pronged socket"), so that the power source could be shared between a lamp and an appliance.

One hundred years later, Panasonic proposed a "Dual Usage Concept" with the goal of redefining existing power lines as information lines. To attain this goal and invent next-generation infrastructures, Panasonic has been working on research and development and demonstration experiments for its unique "High-Definition Power Line Communication" or HD-PLC, which uses a wider band than that of conventional PLC and which is now ready for practical use.

Efficiency, safety, and connectivity of HD-PLC

HD-PLC offers superior communication compared to conventional PLC in terms of efficiency, safety, and connectivity.

First, in terms of communication efficiency, Panasonic's unique technology, called "Wavelet OFDM", was adopted for the digital signal modulation during data transmission. This reduces the processing load by 45.5% and memory usage by 12.5%, relative to conventional methods (FFT OFDM), achieving a significant increase in the communication speed (a data communication speed of about 1 Gbps is possible when coaxial cable is used). The method also reduces the chip size and halves the power consumption, making HD-PLC highly efficient. In addition, "channel estimation technology" (used to optimize the amount of information according to the transmission characteristics of each channel) provides high-speed stable multiplex communication.

In terms of cyber security, the "AES-128" encryption standard was adopted for increasing data security and privacy. Furthermore, multiplex communication, mentioned earlier, makes it difficult to tap data from a single channel (for example, at any one outlet).

The conventional technology was limited in terms of the maximum number of connections and the communication distance: A connection could be made between only two terminals situated no more than a few hundred meters away.
In the case of Panasonic HD-PLC, considerable research and development effort has been undertaken on realizing a "multi-hop function", whereby packets are relayed by selecting optimum communication channels of up to ten stages. This was adopted as a standard feature of the technology and it has allowed to increase the number of connected terminals up to 1024, which can be installed up to several kilometers apart.

Illustration of the communication path automatically changing when the communication line becomes congested.  The “multi-hop function” enables the transmission of data to more than 1,000 terminals. It also allows long-distance transmission over several kilometers, greatly expanding the communication area.

Expansion of the use of HD-PLC

Given its superb communication performance, HD-PLC is expected to be used not only in existing locations and for existing applications but also in a wider range of fields and in a more flexible manner. The use of HD-PLC eliminates the need to run new wiring, which not only saves materials and weight, but also circumvents the huge effort required to lay control lines, while being applicable to locations that are hard to reach wirelessly, such as outdoor luminaires and the exteriors of houses. Even in the case of temples, shrines, and other cultural properties, where such work has conventionally been difficult, and in demanding environments such as underground tunnels and storage dams, it is now possible to create networks relatively easily by combining existing lines with wireless and other existing technologies.

With the goal of promoting the use of HD-PLC, demonstration experiments are underway at the "Panasonic Stadium Suita" and "Panasonic Center Tokyo". These experiments include "control of lighting facilities" using existing three-phase power lines, "leakage measurement", and a crowd guidance system, called "Smart Guide", that is based on outdoor power lines.

Photo: Lights installed on the stadium roof above the spectator stand

"Control of lighting facilities" using existing three-phase power lines

Photo: Without the “Smart Guide” crowd guidance system

"Smart Guide" crowd guidance system

Photo: With the “Smart Guide” crowd guidance system

To illustrate Panasonic’s "smart street lamp system", which was launched commercially in 2017 and which is expected to be widely adopted in the future, several street lamps equipped with IP cameras and PM2.5 sensors have been installed along a path. By connecting them together with an HD-PLC multi-hop connection, it is possible to provide additional functions such as "dimming control", "fault detection", "video surveillance", and "WiFi hotspot installation" throughout a town.

Adopting the domestic IoT foundation technology for international standards

Panasonic has been promoting the HD-PLC technology since 2000. To promote the adoption of this technology in the rest of the world, Panasonic has launched an industry group, named the "HD-PLC Alliance". This group has been working on standardization activities in collaboration with related companies, on ensuring compliance with the regulations of China, Japan, European countries, and the United States and offering "HD-PLC" licenses in anticipation of the expansion of the market.

HD-PLC logo

In 2018, the specification based on the Panasonic-proposed fourth-generation HD-PLC technology was adopted in the Working Draft of the IEEE 1901.3 international standard. In addition to the Wavelet OFDM method, adopted in the IEEE 1901*2 standard, a new technology, unique to Panasonic, which can increase the communication distance and scale communication by controlling the frequency band according to the degree of utilization, will be incorporated into the international standard.

  • *1 HD-PLC: Name of a high-speed power line communication system advocated by Panasonic Corporation, and which is a trademark or registered trademark in Japan and other countries. PLC is an abbreviation for power line communication.
  • *2 IEEE 1901: Standardization Working Group of the Institute of Electrical and Electronics Engineers (IEEE), responsible for addressing communications standards.

Latest trends

Panasonic will continue to support the IoT society with new network foundations through the ongoing development and promotion of HD-PLC.